AVANTI - paving the way to space debris removal

Based on the confidence gained during the first autonomous approach, a second rendezvous has been exercised during the few remaining days of the experiment. The objective was to explore the behavior of the autonomous vision-based GNC system at mid to close range.

Finally, after having extensively investigated the close-range region, on the 17th of November we started drifting apart from Beesat-4. The objective of the following days was to demonstrate the primary goal of AVANTI: the capability to approach a noncooperative target from 10km to 1km fully autonomously.

Starting from a few hundred meters, a challenging approach to a few dozen meters was successfully exercised last week. Not really an autonomous rendezvous though: the main objective was rather to collect relevant experience at mid to close range.

During the first two weeks of experiment we approached BEESAT-4 very closely already three times. Particular interesting for us was to explore the phase below 1 km of relative distance, since here many phenomena take place: the cubesat starts appearing very bright and large in the pictures, and the differential aerodynamic drag perturbation drastically changes, due to the tracking observation attitude profile that is required to keep the cubesat in the camera field of view.

As soon as the commissioning phase of the AVANTI experiment could begin, in parallel to the vision-based navigation task, we started performing several activities to stepwise checkout and verify a certain number of functionalities.

Finding the Bee - Originally foreseen before the ejection of BEESAT-4, the commissioning of AVANTI could only take place after the separation. This delay was in a sense better for the experiment, since it allowed us doing the preliminary functional tests with a real target in the field of view of the camera. The first attempt to observe the picosatellite was performed only twelve days after the separation.

On the 9th of September this year BIROS released in-orbit the BEESAT-4 picosatellite by means of its Single Picosatellite Launcher (SPL). This device is a spring-based mechanism accommodated on BIROS with the ejection track parallel to the z-axis of the spacecraft body frame.

The AVANTI experiment has been designed based on the experience collected in 2012 during the so-called ARGON experiment. ARGON (Advanced Rendezvous demonstration using GPS and Optical Navigation) was the one of the first attempts for the German Aerospace Center to build up expertise in the field of vision-based approach to a non-cooperative object. It used the two satellites of the PRISMA formation-flying mission for the sake of the experiment:

On-orbit servicing and debris-removal missions are currently drawing the attention of national and international space agencies due to the versatile and strategic applications they could enable.
These complex missions require the raising of the technology readiness level in several involved key technological fields (e.g., guidance navigation and control algorithms, robotics and clamping devices, communication architectures). In this framework, the AVANTI experiment represents the in-flight technological demonstrator of one of the on-orbit servicing essential enabling technologies.